condition mean min max ZT0-3 6.040865 6.040865 6.040865 ZT4-7 4.271575 4.271575 4.271575 ZT8-11 5.15802 5.15802 5.15802 ZT12-15 5.0562000000000005 5.0562000000000005 5.0562000000000005 ZT16-19 6.4361999999999995 6.4361999999999995 6.4361999999999995 ZT20-23 5.42163 5.42163 5.42163